The present invention generally relates to an apparatus, method, system for the determination of the aggregation rate of red blood cells. More specifically, the invention concerns a method, system, and the relative apparatus used to determine the aggregation rate of red blood cells, and other parameters related to these, such as viscosity, deformability, elasticity, density, in the field of in vitro medical analyses, using optical systems after or during inducted forces for red blood cell disruption and redistribution generated by ultrasound waves.
The state of the art for the determination of a test value corresponding to blood subsidence from a aggregogram or syllectogram of a blood sample is ascertained by reference to the article “Syllectometry, a new method for studying rouleaux formation of red blood cells” by Zijlstra published in 1963.
Aggregation is the first of three phases describing the sedimentation rate that is composed by: 1) Aggregation 2) Precipitation and 3) Packing. Erythrocyte Sedimentation Rate, which Westergren method is considered the gold standard method, is extensively used as a screening test for the determination of inflammatory status of a patient.
In the sedimentation phenomenon, aggregation is the first and the fastest among the three phases, which lasts less than two minutes, where red blood cells (RBC) forming chains (face to face aggregates) termed “Ruloux”. This phase is reversible by mixing action, due, for example, with the repeated inversion of the test tube containing the sample. Rulouxformation causes are still not completely clear; the most important causes are related to proteins dispersed in plasma, such as fibrinogen. However, it is known that aggregation between RBC is strictly related to infections, inflammatory and connective tissue disorders.
A second stage aggregation phase, after Ruloux formation, spherical aggregates are formed between Ruloux with uniform increased mass, that sediment, after an initial acceleration, at constant speed conforming Stokes law. This second phase is called precipitation, and is the phase evaluated during the Westergren (WG) standard method.
As Stokes law describes that the constant speed is a balance between gravity force, viscosity and hydrostatic stress. The viscosity in a fluid as plasma is heavy affected by thermal effects and can modify sedimentation rate independently the encountered Ruloux level. Also lipids dispersed in plasma, in conjunction with lipoproteins, can increase viscosity and reduce the precipitation phase and the resulting sedimentation rate measure.
Syllectometry is a measuring method that is commonly used to determine the red blood cell aggregability, which can be related to consequent sedimentation rate. As reference, in syllectometry light is incident to a layer where the sample is exposed to shear stress. Luminous flux attenuation/increase or backscatter ultrasound wave are used for determination of variations in sample density after the abrupt stop of driving mechanism. The subsequent time-dependent plot is called syllectogram.
Therefore, there remains a need in the prior art for an apparatus, method, system for the determination of the aggregation rate of red blood cells which does not require a stopped flow technique for aggregation kinetic detection.